In brief, an extensible, syncable tool for making lightweight personal Markdown wikis. Emphasis on being very smooth and stylish. Emphasizes giving you a lot of tools that can suit a lot of writing/note taking workflows.

If I were to need to start writing a book this week, this is probably where I'd organize the research and composition.

It's a note-taking app that emphasizes non-linear writing.

You can use it as a journal, personal wiki, knowledge base, task management, or just a Markdown text editor. There are hundreds of plugins that make it easy to tailor the app to your needs.

It's also focused on privacy and future-proofing your notes. All your data is stored locally in a folder of plain text files.

(Advanced) note taking, often used in the Personal Knowledge Management (PKM) & "Second Brain" community.

It’s a note-taking application like Evernote but open source. Has native apps. You can sync using a self-hosted sever easily. Works great on mobile too. Update: Oops. I always thought it was Open Source. I started using it after learning about it a HN thread some time ago. Downloaded and started using and it worked so good I didn’t have to look back about it.